The present invention relates to an endless track for a vehicle. More particularly, the present invention relates to a track which is particularly well suited for a snowmobile.
A rubber-band track is found on off-road motor driven vehicles which are designed to travel on grounds that could not adequately support wheels or on which traction forces could not be suitably applied with the use of wheels. A rubber-band track consists essentially of an endless band of a reinforced material that is longitudinally flexible so as to follow the curvature around drive and idler sprocket wheels. Each track is designed to support a portion of the weight of the vehicle and apply a traction force on the ground.
Without excluding any other applications, tracks for vehicles traveling at moderate or high speeds, which are essentially snowmobiles, are the prime interest of the present invention. The snowmobiles are then used in the present description as the main application for the tracks and the method in accordance with the present invention.
A snowmobile is equipped with a rubber-band track that features an endless body made of a reinforced rubber material with longitudinally spaced and transversely disposed stiffeners embedded in the rubber material between the sides of the track. The body defines a central band portion and opposite lateral band portions that are located on the sides of the central band portion. The opposite lateral band portions are separated from the central band portion by a corresponding row of holes. Each row of holes generally cooperates with the teeth of a corresponding pair of drive and idler sprocket wheels. The track is positioned under the chassis of the snowmobile and supports most of the weight. A pair of front ski-like runners are provided to steer the snowmobile and support the other portion of the weight.
The body of the track has a ground-engaging outer side and an inner side. The inner side cooperates with a suspension system. The weight of the track by either a pair of slide rails or a plurality of bogey wheels that are mechanically connected to the other parts of the suspension system. Alternatively, the drive and idler sprocket wheels may engage driving lugs that are inwardly projecting from the inner side of the track. The suspension system is also used to support the track with respect to lateral movements.
Suspension systems using slide rails are the now used on almost every new models of snowmobiles. While some bogey wheels are present at strategic locations, all the weight from the suspension system is transmitted to the track by the pair of slide rails. The slide rails cooperate with the inner side of the track, more particularly with the portion of the track that engages the ground. Each slide rail typically comprises an expandable low friction runner that engages the inner side of the track and that is replaced whenever it is worn to a given extent. Now, to further lower the friction coefficient between the inner side of the track and the bottom face of the runners, the track is equipped with a plurality of metallic clips. The clips are conveniently aligned with the row of holes and crimped over the material on the inner side between two successive holes. This material is, in most cases, surrounds a corresponding stiffener passing between the central band portion and the lateral band portions. Conventional clips are also used for laterally guiding the track. To do so, all or a large number of the clips are provided with a side flange that is configured and disposed to slide on the side of a respective runner.
Formerly, clips were generally provided at every available space, which are referred to as the clipping sites. There are usually from 24 to 80 clipping sites on each side of the track. Few models have clips that are omitted at regular intervals. In all cases, the clips come in contact at regular intervals with the runners when the track rotates. This repetitive contact generates a noise which varies in function of the rotation speed of the track. The noise often becomes annoying and unpleasant, especially when traveling over long distances.
One aspect of the present invention is to lower the noise level generated by the snowmobile track while rotating by mixing clip sequences on each row of clipping sites so as to lower the overall noise level generated by the track while rotating. Each clip sequence comprises one or more successive clips and one or two successive clipping sites without clip.
Another aspect of the present invention is to lower the weight and manufacturing costs of the track by omitting some clips at various clipping sites.
These and other aspects and advantages of the present invention are described in or apparent from the following detailed description of a preferred embodiment made in conjunction which the apparent figures.